A simple polyol one-shot synthesis of Maghemite and Hematite from inexpensive precursors

The two significant phases of iron oxide, namely, Hematite and Maghemite, have attracted the attention of scientists owing to their excellent magnetic and catalytic properties. Herein, we report a novel precursor salt-dependent single-step modified polyol method using the sol–gel auto combustion of metal nitrates or chlorides in ethylene glycol to synthesize magnetic alpha (α) and gamma (γ) Fe₂O₃. The samples are then characterized to analyze the structural, morphological, electrical and magnetic properties. The XRD results show that the alpha and gamma Fe₂O₃ exhibit hexagonal and cubic crystal structures, respectively. From the FESEM micrographs, the morphology changes are visible; for alpha Fe₂O₃ a plate-like structure is seen, whereas the gamma Fe₂O₃ particles exhibit a spherical morphology. The EDS spectrum indicates that the samples contain no impurity as the spectrum shows strong peaks for Fe and O. The Fe-O bond corresponding to stretching vibration is observed in the FTIR spectrum. The UV–Vis spectrum shows bandgap energy of 2.8 eV and 2.4 eV for alpha Fe₂O₃ and gamma Fe₂O₃ respectively. The surface of the prepared nanocomposite contains only Fe and O, which is confirmed from XPS analysis. The soft ferromagnetic behaviour of gamma Fe₂O₃ and antiferromagnetic behaviour of alpha Fe₂O₃ is evident from the magnetic measurements. The impedance analysis is also carried out, and the dielectric constant for alpha Fe₂O₃ is 88, and that of gamma Fe₂O₃ is 167.